import math
while True:
    try:
        hight = eval(input("输入身高M："))
        weight = eval(input("输入体重KG："))
    except NameError:
        print("请输入数值")
    PIM=weight/(math.pow(hight,2))
    print(math.pow(1.68,2))
    print(PIM)
    flag = input("是否继续，退出输入：yes，是则随意输入！")
    print(flag)
    if flag == "yes":
        break